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I don't have access to an acoustic other than my teacher's piano, so I wanted to know if this behavior is indeed normal or if only Kawai pianos display it. If so, then what is the reason that C also vibrates?

Yes quite normal .... any acoustic piano would do the same! A broken damper in that area would allow all sorts of harmonics to vibrate in sympathy, and what you're doing is inducing the same effect on your digital.

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Concert Tuner & Technician for the past 49 years in the United Kingdomand Member of the Pianoforte Tuners' Association (London)www.jphillipspianoservices.freeindex.co.uk : E-mail jophillips06@aol.com

It is not normal. I can hear the C's fundamental clearly and that should not be. There should only be a wash of various higher overtones of C maybe depending on the other note struck. Does it do the same thing on other notes?

This certainly is not wanted, nor does it serve any harmonic purpose. As far as it being "normal" for this model, you should first determine if it exibits the same thing on other notes also...or is it just this C note. Secondly, try and find out if somebody elses Kawai (same model) does the same thing. There may be some voltage bleed through on a circuit board where two parallel crcuits are not properly insulated from each other. There is no sympathetic vibration going on since this DP uses sampled sound...no physical strings present.

I'll just shut up then Bogs ..... Clearly I and Kawaii are talking a load of rubbish !

_________________________
Concert Tuner & Technician for the past 49 years in the United Kingdomand Member of the Pianoforte Tuners' Association (London)www.jphillipspianoservices.freeindex.co.uk : E-mail jophillips06@aol.com

I'll just shut up then Bogs ..... Clearly I and Kawaii are talking a load of rubbish !

Johnkie, if it's a bit of consolation, I tried to say the same in another thread on the digital piano forum here on PW, with similar success. Goes to show how well people know the instruments they are working with...

Perhaps this is best asked in the digital forum? As this is the acoustic piano forum?

As for acoustic pianos, if properly tuned, John is right. If you hold down C-4, then play E-4, G-4, C-5 etc., all the way up, then every single one of those notes will sound through on that one C-4 which is not being shut off by the damper because you are holding it down. That IS normal. It should do it on any key that you choose to play on, however if you play C-4 and make then play D-4, some sound may come through but not like it would if you played notes related to C-4 and probably, not nearly as much so.

I do have to wonder, why in the heck are you doing that in the first place????

I have no idea how it would be on a digital piano because piano tuners (most of us anyway) do not work on these things.

When you write to a company inquiring about their product, there is no guarantee that a qualified person replies with a decent answer. In fact, most companies have a series of defenses you need to wade through to actually get a decent answer from the proper person who knows what they are talking about.

The first line of these defenses are people (often secrataries)known as deflectors. They typically know nothing about the product and throw "canned" form letters or answers back to the inquirer to deflect further inquiries. They don't want to bog down their highest paid employees with customer inquiries. Successive and repeated inquiries will often find their way to the design engineer(s) and quality control folks who have the ability and resources get to the bottom of things and come up with a decent explanation.A first time call or written complaint/request rarely gets to these people unless its a huge safety or liability issue.

I am not an electronics wizard by any means, but can't subscribe to "Electronic bleed through" on a digi piano, especially when Kawaii techs have already been asked if this manifestation is a fault. Generally speaking faulty electronic components result in either something not playing at all, or an uncontrollable cipher

My Guess .... and only a pure guess .... is that the guys at Kawaii have researched the properties of acoustic pianos and incorporated this effect to add realism. It is perhaps a little over exaggerated, but I personally do not consider it to be a fault, more part of Kawaiis intended design.

_________________________
Concert Tuner & Technician for the past 49 years in the United Kingdomand Member of the Pianoforte Tuners' Association (London)www.jphillipspianoservices.freeindex.co.uk : E-mail jophillips06@aol.com

John: Would you really expect to hear the fundamental of C4 if you held the key and pressed C#4 or B3? That is what the video shows, and it is really odd behaviour. I think you might have misunderstood the original post to be honest, or maybe not watched the video?

But they do. Please, people, sit down at your pianos and try for yourself.

Originally Posted By: Johnkie

My Guess .... and only a pure guess .... is that the guys at Kawaii have researched the properties of acoustic pianos and incorporated this effect to add realism. It is perhaps a little over exaggerated, but I personally do not consider it to be a fault, more part of Kawaiis intended design.

Indeed. And that realism makes sense since the situation is not as rarely occuring as it might seem - after all you get these kinds of 'neighbouring resonances' whenever you play notes with the damper pedal down, or in other situations when you hold a chord with one hand and play something in between with the other. Etc.

If you hold down C on an accoustic piano (to lift off the damper) and play the B or C# to either side of it to ghost a tone, you will not hear the fundamental C ring out.There may be some incredibly soft very high order partials excited but nothing even close to what your hearing on the DP. This is not an accoustic phenomenom which I think someone would diliberately want to mimic with a DP (exciting a non related harmonic).

I talked with my brother who is an electrical engineer and he confirmed my original suspicians of "bleed through" not being correct on a digital piano (as another poster mentioned). It could easily occur on analogue systems, hi fi's ect...His suspicians are that its crappy software, if it indeed is not intended to be there. A rogue line of programming or something like that.

So ask the technicians here...Is the fundamental pitch of C something you want to hear when playing its two neighbouring notes to either side?

Accoustic pianos don't audibly display this if you try to ghost the tone using the immediate neighbouring keys. Wouter, I'm not sure what your hearing, but its not happening on any of the accoustic pianos I just checked it on. Theory supports this since B and C# do not contain the fundamental frequency of C between them.

... its not happening on any of the accoustic pianos I just checked it on.

Emmery, I find this hard to believe.

Maurus, in order to excite sympathetic vibration on a string the resonant frequency used to do it must match. What frequency in B or C# can excite the fundamental of C which is beside it? No such frequency exists in either of those notes. The closest note below C, to excite its fundamental frequency is the C note, one octave below it...this is a fact.

Just to make matters clear - what you heard on the video is what happens no matter what key you have depressed, as long as you plan a note a semitone higher/lower, you can hear the depressed key resonating.

The Kawai support guy told me he tested this behavior on Kawai GE-30 and the result is the same. Maurus, who also has a Kawai, said his acoustic piano also exhibits this behavior. I see others here claim the same.

But from the theoretical(physics) point of view, C and C#/B don't share any harmonics [as per the google docs spreadsheet]. It's normal for G and F and E, etc to excite the C strings, but not C# nor B.

Now the question is, are Kawai pianos 'special' and exhibit this behavior? And if so, what is the reason? Someone said the hammer may hit the strings next to it, and thus set it in motion [so no sympathetic resonance involved and thus no violation of the physics laws regarding vibrating strings]. This theory is also supported by the fact that if I silently press C4 on the Kawai digital, C#4 and B3 excite the C4, but neither C#3 nor B2 (also C#5/B4) do.

All strings are not damped in a piano. Typically the dampers stop at a point in the treble where strings tend not to have as much sustain as lower notes. I have never seen a piano with dampers going up to C8. What is it that you mean by "slightly damped"? Short sustain is not dampening. Natural decay of a sound on a string is not dampening either.

Secondly, if you notice, I refrain from using generic terms such as "respond" when in fact I refer to a property of a string picking up on another strings vibration as "sympathetic" resonance or vibration. The entire bridge and soundboard of the piano vibrates from one note playing. Many other strings are connected to the same bridge (segment) and vibrate at the bridge connection because of their physical connection. Only the undamped strings will pick up on this connection and only if they share the same frequencies and partials of the excitation frequency. Properly dampened strings will not produce audible sympathetic vibrations of this nature....thats why they are damped.

They do not however, all sympathetically vibrate at like pitches unless they share the fundamental frequency or partial ladder. Hold down C5 and play C4 (staccato)and you will clearly hear the fundamental of C5 excited by C4's first partial (along with numerous other coincidental partials farther up the ladder). If you do the reverse however and hold down C4 and strike C5...you will hear C4's first partial excited...not its fundamental...C5 does not have the coincidental frequency to do so...its lowest frequency is twice that of C4's lowest frequency.

Now using unrelated notes such as B or c# to excite the fundamental frequency of C that lies next to it, will simply not work. THEY SHARE NO COMMON FREQUENCY WITH C'S FUNDAMENTAL. You may hear a very faint busy mix of super high partials way up the ladder, if they happen to be coincidental, but definately nothing clear or concise and DEFINATELY NOT THE FUNDAMENTAL FREQUENCY OF C AS HEARD IN THE DP.

If I try it on my pianos, I get a lot of noise out of the C, with a definite bias towards the C pitch. I would think that there is enough coupling of energy through the bridge to excite the string, and most of it will be in C. It is not as strong as if I hold the C and play the C an octave above it, however.

Perhaps rather than saying "this shouldn't happen" it would be better to think of possible reasons why in fact .... it does!

Sympathetic vibrations and harmonics are without doubt part of the overall character of pianos, but adjacent notes being influenced might well be the result of closeness of frequency. When there is relatively little difference between adjacent notes, it may be more a case of a phase shift causing an interference beat that excites the non-played note.

This would account for the lack of like similar behaviour if trying to emulate the same scenario using octaves above and below .... their frequencies being way to far from the resonant frequency of the un-played note.

I can see that kawaii (and other excellent manufacturers) have most likely tried to be as close as possible to the real thing, but whereas an acoustic piano needs quite a powerful strike on an adjacent key to get this effect, digitals tend to have software designed to trigger certain results, on a "if that .... then this" type of senario.

If I had anything to do with improving digital piano software design, I would be looking at linking the velocity side of the design to match more closely the effect on adjacent notes .... more so in the bass and tenor sections where frequencies are closer.

Lets not get into a running battle though ..... I'm just thinking out loud

_________________________
Concert Tuner & Technician for the past 49 years in the United Kingdomand Member of the Pianoforte Tuners' Association (London)www.jphillipspianoservices.freeindex.co.uk : E-mail jophillips06@aol.com

Emmery (and Johnkie and others). If one starts to do physics, one should get the physics right. In terms of physics every string that loses some of its energy to its surroundings, by whatever mechanisms, is what physicists call a "damped" oscillator. (That has nothing to do with the dampers in a piano.) And the physics tells you that any damped oscillator does not only react to (= acquires energy from) harmonic vibrations that reach it, but to frequencies very close to its fundamental mode as well. (*In addition*, there is the response of the string to the noises made by the hammer when hitting strings closeby, and other complex effects, depending on the construction and the circumstances. That response leads to an excitement of certain overtones in a given string, just as BDB reports.)

But whatever physics tells you, you have hands to play and ears to listen to your piano(s).

Has it occured to you that C# or B have no harmonic/musical connection to C. Nor do we as tuners use two attached semitones as a tuning interval. Also, manufacturers strive to hit the string with the hammer near the node point of an unwanted but naturally occuring partial (eg. C3- A#5 or D6). What logic would there be to have the sound of C3's fundamental in the mix of C#3's sound or vice versa? I can't imagine a software engineer deliberately trying to do this.

I just checked my C3 note with MatLab spectrum analyser and it's fundamental does not show after trying to excite it with B2 and C#3. My ETD RCT is not picking up on it either with full gain and the mike cranked up. Most importantly, I'm not hearing it either.

I would however love to hear any accoustics/physics/scientific explanation or formula that explains how non coincidental frequencies bring out sympathetic vibration or resonance in an object or string in a supportive manner. The imput of the vibration would have to be equal to the natural resonance of the object to build sound...anything other than this would cancel it by vibrating out of frequency with the resonance pattern.

One more experiment pretty much confirms what I said. Playing a note adjacent to a note that is held silently will excite the silent note through energy transferred mechanically. The proof of this is to hold a note at the break, and try the adjacent note on the same bridge and the adjacent note on the other bridge. The one on the same bridge will make the note held silently sound louder than the one on the other bridge, which has a more distant mechanical connection.

You could describe it this way: when you first strike this adjacent key, there is a sudden pressure wave that is somewhat close to the frequency of the adjacent note. If you hit this note VERY hard and staccato, you can induce a very small amount of movement in an adjacent string. It's not the same thing as sympathetic resonance however. Achieving a note in an adjacent string requires you to make the excitation note very short, because if it is allowed to keep vibrating for a time, it will interfere destructively with the adjacent note. This effect is reliant on the non-struck string not being able to really "see" the frequency of the string that is exciting it. If you try it, you can hold down a B and belt a C really hard and short, you will hear a faint B coming through. This is caused by this pressure high wave which can induce movement in the string. If you do the same thing, but hold the C for a couple of seconds, the B will pretty much disappear. That's because the frequencies are unable to couple, instead they cancel. There is nothing to sustain the B. Real sympathetic resonance involves genuine coupling of frequencies and it will continue for as long as both notes are free to ring.

I would consider it a waste of time to bother trying to incorporate this effect in a digital piano. It also comes through far too loud in the clips of the Kawai. This is a problematic emulation of sympathetic resonance. Of course, you can turn the resonance down on a DP, but that punishes the resonances that should be relatively strong - octaves and fifths.

Bogs, I'm wondering - did you try turning off the sympathetic resonance in the digital? I do not work with digital pianos much, but I have used some of our digital models and this is an adjustable parameter. The functions in the digitals are made to simulate the sounds created in acoustic pianos as closely as possible.

Now Emmery wrote: <When you write to a company inquiring about their product, there is no guarantee that a qualified person replies with a decent answer. In fact, most companies have a series of defenses you need to wade through to actually get a decent answer from the proper person who knows what they are talking about.

The first line of these defenses are people (often secrataries)known as deflectors. They typically know nothing about the product and throw "canned" form letters . . . . . . etc.>

Emmery, I don't know where this comes from, but it is a load of nonsense, to put it politely. It amazes me to read these kind of statements made in forums stating vividly imagined fiction in an emphatic and authoritative manner.

First of all, there are no "secretaries" at Kawai. All technical support calls for digitals go directly either to an electronics technician who knows the products inside and out (Juan), or to the person who is responsible for developing the sounds and functionality of the instruments, Alan. There is also a parts person to take parts orders. All technical support calls for pianos go directly to a piano technician (there are 3 at Kawai America including me), or to a parts specialist. If a call or e-mail goes to the wrong person, everyone in the company knows to forward it directly to the correct person in service, and no one would do anything resembling what you wrote.

So Emmery, back off a little and realize that piano companies are staffed by people just like you. Kawai and other piano makers are not huge corporations with layers of staffing intent on deflecting issues. All of us have the attitude that solving a problem is much better for everyone than letting it go unresolved.

Don, my posting on how many companies operate to handle questions/complaints was generic, even though it was within the topic of a Kawai related issue. Its just something people have to watch for these days. From your explanation, Kawai seems to handle this better than most companies. Try getting technical advice on a Young Chang/Kurzwiel DP and you will know what I mean by the term "deflection".

Still, I find it highly doubtful that a service tech, design/software engineer, and programmer are one in the same person or that any of these specific professions (Kawai or anyone else) requires full competancy/training/related qualifications, of the other two. It is still worthwhile to try and make sure one is talking to the right person, or confirm that the company is delegating questions/complaints to the right people. Eg. Programmers can verify if an engineering spec was properly executed in the software. Engineers can verify if the foundations of the specs are in line with what the product is supposed to do. Technicians in the field can replace circuit boards, diagnose problems ect..

The answer given to the OP by Kawai that the sound heard on playing those notes is "normal". This does not indicate if it was intended by design, or just a byproduct of other factors (flawed programming or an adjustable setting for eg.) Squeaky body parts on a 1970 Vega is pretty "normal" if you ask a mechanic or an owner of one. GM certainly didn't intended it to be by design.

On acoustic pianos numerous things are done to lessen or eliminate unwanted sounds or harmonics. Cloth is woven into parts of strings to dampen them, hammer strike point coincides with node locations of unwanted partial(s), scaling design tries to lessen inharmonicity, tone issues or uneven downbearing. I think its far fetched to believe a DP will try to incorporate into its design something which an accoustic piano manufacturer effectively went out of their way to eliminate. Certainly not to the degree that can be heard in the OP's sound sample. Besides, there are numerous other wanted things they are still trying to emulate off accoustic pianos and not being 100% succesful with.